<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>js的while循环</title>
</head>
<body>
<p>点击下面的按钮，只要i小于5就一直循环代码块。</p>
<button onclick="myFunction()">点击这里</button>
<p id="demo"></p>
<script>
    function myFunction() {
        var x="",i=0;
        while(i < 5){
            x=x + "该数字为 " + i + "<br>";
            i++;
        }
        document.getElementById("demo").innerHTML=x;
    }
</script>
</body>
</html>